This invention relates to bio-feedback. More particularly this invention relates to method and apparatus for displaying data related to biological functions of a subject to the subject in such form that the subject can learn to interact with the display to control the biological functions, and in which the display is adjusted to enhance the ability of the subject to interact with the display as the values of the physiologic functions being monitored vary.
Bio-feedback as practiced in the prior art involves the display to a subject of signal values related to physiologic functions by means of audible tones, meter readings, and the like. It has been found that the magnitude of variations of values of physiologic functions, and the rates at which such values change with varying subjects at differing levels of capability in bio-feedback control are such that either the display device will be insufficiently sensitive to allow the subject to discern minor changes in the values of a physiologic function, or will be of such limited range that data will go "off scale", or otherwise beyond the display capabilities of the display device. The prior art has attempted to deal with this situation by compressing data by the use of logarithmically responsive display devices, or by the use of a plurality of fixed, discrete, manually switchable display ranges. The use of a logarithmic scale is a limited solution to the problem, because, even with compression, a fixed finite scale is employed in which the possibility of an off scale value still exists. The use of logarithmic scales also presents the disadvantage that, in the compressed area of the scale, resolution is lost. Manual range switching has the disadvantages of requiring the continuous attention of an operator, providing, upon range switching, a drastic, arbitrary, change of display indication, which may momentarily confuse the subject until he realizes that a range change has taken place, and still only provide a small number of available ranges in practical systems so that displays can not be fully optimized for subject/display interaction purposes.
It is, accordingly, an object of this invention to provide bio-feedback method and apparatus in which the display of values of physiologic data from the subject is perceptually optimized to facilitate the interaction between the subject and the display.
It is another object of this invention to accomplish such perceptual optimization by continuously adjusting the scale of the display as functions of the values of the physiologic data and rate of change of such values.
Another object of the invention is to provide a display of a metric simultaneously with the display of the values of the physiologic data.
Another object is to change the display of of the metric coincidentially with a change of range scale to reduce confusion in the subject by immediately indicating the display adjustment to him.
It is another object of this invention to provide for a very large number of available display scale ranges, determined and displayed automatically solely from the physiologic data provided by the subject.
It is another object of this invention to provide for the simultaneous display of values of physiologic data from the subject and a target value toward which the subject is to attempt to direct his physiologic response value.
It is another object of this invention to provide for the continuous modification of the target value, automatically, as a function of the values of the physiologic data from the subject.
Briefly, and in accordance with one embodiment of this invention, a sensor detects a physiologic function of a subject and provides an electrical signal related thereto. The signal is digitized in a converter into a stream of digital signals corresponding to the values of the biological signal over time. A plurality of digital signals are processed for display to the subject, and statistical functions are determined from such plurality of digital signals to determine the optimum scaling of the display, and the appropriate target value to be displayed. The display device is driven to display the appropriate target or the metric of the optimal scale range, or both, simultaneously with the display of values of the physiologic functions provided by the subject. The statisical functions are continuously redetermined, and the display is modified solely responsively to the characteristics of the digitized data stream from the subject.